Rheology modification of elastomers

ABSTRACT

The present invention includes a process of preparing a coupled polymer comprising heating an admixture containing (1) at least one elastomer comprising ethylene and at least one comonomer which is selected from alpha olefins having at least 3 carbon atoms, dienes and combinations thereof and (2) a coupling amount at least one poly(sulfonyl azide) to at least the decomposition temperature of the poly(sulfonyl azide) for a period sufficient for decomposition of at least 80 weight percent of the poly(sulfonyl azide) and sufficient to result in a coupled polymer having a gel content of less than 2 weight percent. The invention includes compositions comprising the reaction product formed by the inventive process. The invention additionally includes articles which comprise a composition of the invention particularly when the article is formed from a melt of the composition.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.09/129,161, filed Aug. 5, 1998, now U.S. Pat. No. 6,376,623.

This application claims the benefit of U.S. Provisional Application No.60/057,582, filed Aug. 27, 1997 which is incorporated by referenceherein in its entirety.

This invention relates to coupling of polyolefins, more specificallycoupling of elastomeric polyolefins.

As used herein, the term “rheology modification” means change in meltviscosity of a polymer as determined by dynamic mechanical spectroscopy.Preferably the melt strength increases while maintaining the high shearviscosity (that is viscosity measured at a shear of 100 rad/sec by DMS)so that a polymer exhibits more resistance to stretching duringelongation of molten polymer at low shear conditions (that is viscositymeasured at a shear of 0.1 rad/sec by DMS) and does not sacrifice theoutput at high shear conditions. An increase in melt strength istypically observed when long chain branches or similar structures areintroduced into a polymer. Rheology modification is particularlyimportant when the polyolefins are elastomers.

The term “elastomer” was first defined in 1940 to mean syntheticthermosetting high polymers having properties similar to those ofvulcanized natural rubber, e.g. having the ability to be stretched to atleast twice their original length and to retract very rapidly toapproximately their original length when released. The elastic recovery(that is recovery of original dimension) of an elastomer is generally atleast 40 percent, preferably at least 60 percent, and more preferably atleast 70 percent after the sample is elongated 100 percent of anoriginal dimension at 20° C. according to the procedures of ASTM D 4649.Representative of these “high polymers” were styrene-butadienecopolymer, polychloroprene, nitrile butyl rubber and ethylene-propylenepolymers (aka EP and EPDM elastomers). The term “elastomer” was laterextended to include uncrosslinked thermoplastic polyolefin elastomers,that is, thermoplastic elastomers (TPEs).

ASTM D 1566 defines various physical properties of elastomers, and thetest methods for measuring these properties.

A dilemma faced in the production of commercially viable curedelastomers is that a high weight average molecular weight is generallydesired to improve physical properties such as tensile strength,toughness, and compression set, in the cured product, but the uncuredhigh molecular weight elastomers are more difficult to process thantheir lower molecular weight counterparts. In particular, the highermolecular weight uncured elastomers are typically more difficult toisolate from solvents and residual monomer following polymerization ofthe elastomer. The uncured higher molecular weight elastomers are alsotypically more difficult to extrude at high rates, since they aregenerally prone to shear fracture at lower extrusion rates and requiremore power consumption by polymer processing equipment such as batchmixers, continuous mixers, extruders, etc., and cause increased wear onthe parts of such equipment exposed to high shear stresses, such asexpensive extruder components. These disadvantages reduce productionrates and/or increase the cost of production.

Often, a relatively low molecular weight elastomer produced then isfully crosslinked in a final product to obtain the desired tensilestrength, toughness, compression set, etc. The relatively lowermolecular weights of elastomer are easiest to produce.Disadvantageously, however, a low molecular weight of an elastomer alsoin most instances, corresponds to a low “green strength” (i.e., strengthprior to crosslinking). The disadvantage is particularly noticeable inapplications such as coating wire and cable, continuous extrusion ofgaskets, etc., where low green strength results in sags or unevenpolymer thickness. Rheology modification of a lower molecular weightelastomer, however, is an advantageous manner to solve the problem.

Polyolefins are frequently rheology modified using nonselectivechemistries involving free radicals generated for instance usingperoxides or high energy radiation. However, chemistries involving freeradical generation at elevated temperatures also degrade the molecularweight, especially in polymers containing tertiary hydrogen such aspolystyrene, polypropylene, polyethylene copolymers etc. The reaction ofpolypropylene with peroxides and pentaerythritol triacrylate is reportedby Wang et al., in Journal of Applied Polymer Science, Vol. 61,1395-1404 (1996). They teach that branching of isotactic polypropylenecan be realized by free radical grafting of di- and tri-vinyl compoundsonto polypropylene. However, this approach does not work well in actualpractice as the higher rate of chain scission tends to dominate thelimited amount of chain coupling that takes place. This occurs becausechain scission is an intra-molecular process following first orderkinetics, while branching is an inter-molecular process with kineticsthat are minimally second order. Chain scission results in lowermolecular weight and higher melt flow rate than would be observed werethe branching not accompanied by scission. Because scission is notuniform, molecular weight distribution increases as lower molecularweight polymer chains referred to in the art as “tails” are formed.

The teachings of U.S. Pat. Nos. 3,058,944; 3,336,268; and 3,530,108include the reaction of certain poly(sulfonyl azide) compounds withisotactic polypropylene or other polyolefins by nitrene insertion intoC—H bonds. The product reported in U.S. Pat. No. 3,058,944 iscrosslinked. The product reported in U.S. Pat. No. 3,530,108 is foamedand cured with cycloalkane-di(sulfonyl azide) of a given formula. InU.S. Pat. No. 3,336,268 the resulting reaction products are referred toas “bridged polymers” because polymer chains are “bridged” withsulfonamide bridges. The disclosed process includes a mixing step suchas milling or mixing of the sulfonylazide and polymer in solution ordispersion then a heating step where the temperature is sufficient todecompose the sulfonylazide (100° C. to 225° depending on the azidedecomposition temperature). The starting polypropylene polymer for theclaimed process has a molecular weight of at least about 275,000. Blendstaught in U.S. Pat. No. 3,336,268 have up to about 25 percent ethylenepropylene elastomer.

U.S. Pat. No. 3,631,182 taught the use of azido formate for crosslinkingpolyolefins. U.S. Pat. No. 3,341,418 taught the use of sulfonyl azideand azidoformate compounds to crosslink of thermoplastics material(PP(polypropylene), PS (polystyrene),PVC (poly(vinyl chloride)) and theirblends with rubbers(polyisobutene, EPM, etc.).

Similarly, the teachings of Canadian patent 797,917 (family member of NL6,503,188) include rheology modification using from about 0.001 to 0.075weight percent polysulfonyl azide to modify homopolymer polyethylene andits blend with polyisobutylene.

In the case of elastomeric polymers containing ethylene repeating unitsin which the preferred comonomer content is about 5-25 mole percent, andpreferably a density less than about 0.89 g/mL, it would be desirable tohave a better mechanical properties such as elongation and tensilestrength than would be achieved in the starting material or by couplingusing the same chemical equivalents of free radical generating agentlike a peroxide.

SUMMARY OF THE INVENTION

Polymers coupled by reaction with coupling agents according to thepractice of the invention advantageously have at least one of thesedesirable properties and preferably have desirable combinations of theseproperties.

The present invention includes a process of preparing a coupled polymercomprising heating an admixture containing (1) at least one elastomercomprising ethylene and at least one comonomer which is selected fromalpha olefins having at least 3 carbon atoms, dienes and combinationsthereof and (2) a coupling amount at least one poly(sulfonyl azide) toat least the decomposition temperature of the poly(sulfonyl azide) for aperiod sufficient for decomposition of at least about 80 weight percentof the poly(sulfonyl azide) and sufficient to result in a coupledpolymer having a gel content of less than about 2 weight percent. Theelastomer preferably comprises ethylene, and alpha olefin of at leastthree carbon atoms and optionally at least one diene and preferably hasa density of at least about 0.850 and up to about 0.90 g/mL. Morepreferably the elastomer is an ethylene/octene copolymer or anethylene/propylene/norbornene copolymer. Preferably the polymer isprepared using a metallocene or constrained geometry catalyst and morepreferably has a narrow molecular weight distribution. Optionally theprocess additionally comprises steps (b) fabricating an article from thecoupled polymer and (c) crosslinking the fabricated coupled polymer.

The poly(sulfonyl azide)and elastomer preferably react at a temperatureat least the decomposition temperature and greater than about 150° C.

The invention includes compositions comprising the reaction productformed by heating an admixture containing (1) at least one elastomercomprising ethylene and at least one comonomer which is selected fromalpha olefins having at least 3 carbon atoms, dienes and combinationsthereof and (2) a coupling amount at least one poly(sulfonyl azide) toat least the decomposition temperature of the poly(sulfonyl azide) for aperiod sufficient for decomposition of at least about 80 weight percentof the poly(sulfonyl azide)said reaction product having less than about2 weight percent gel; which compositions preferably have couplingindicated by a viscosity change at a shear frequency of 0.1 rad/sec ofgreater than 5 percent as measured by DMS.

The invention additionally includes articles which comprise acomposition of the invention particularly when the article is formedfrom a melt of the composition. The article is preferably a coating forwire or cable, a tube, a gasket, a seal, roofing, or fiber. Further theinvention includes the use of the composition to form the articles andprocess of formation of the articles by molding or profile extruding acomposition of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Practice of the invention is applicable to any elastomer which has atleast one C—H bond that can react with azide including copolymers withnarrow and broad (including bimodal) weight distribution and comonomerdistribution such as copolymers of ethylene with one or more monomershaving unsaturation, preferably alpha olefins having more than 2 carbonatoms (preferably C3 to C20), (polymers such as ethylene-propylenecopolymer and ethylene-octene copolymer), optionally with an additionalmonomers having at least two double bonds , for instance EPDM or EODM,that is ethylene-propylene-diene or ethylene-octene -diene).

Alpha olefins having more than 2 carbon atoms include propylene,1-butene, 1-pentene, 1-hexene, 1-octene, 1-nonene, 1-decene,1-unidecene, 1-dodecene and the like as well as 4-methyl-1-pentene,4-methyl-1-hexene, 5-methyl-1-hexene, vinylcyclohexene, and the like andcombinations thereof.

Interpolymers useful in the practice of the invention include monomershaving at least two double bonds which are preferably dienes or trienes.Suitable diene and triene comonomers include 7-methyl-1,6-octadiene,3,7-dimethyl-1,6-octadiene, 5,7-dimethyl-1,6-octadiene,3,7,11-trimethyl-1,6,10-octatriene, 6-methyl-1,5-heptadiene,1,3-butadiene, 1,6-heptadiene, 1,7-octadiene, 1,8-nonadiene,1,9-decadiene, 1,10-undecadiene, bicyclo[2.2.1]hepta-2-5-diene(norbornadiene), tetracyclododecene, or mixtures thereof, preferablybutadiene, hexadienes, and octadienes, most preferably 1,4-hexadiene,4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, dicyclopentadiene,piperylene, bicyclo[2.2.1]hepta-2-5-diene (norbornadiene) and5-ethylidene-2-norbornene (ENB).

Polyolefins are formed by means within the skill in the art. The alphaolefin monomers and optionally other addition polymerizable monomers arepolymerized under conditions within the skill in the art, Suchconditions include those utilized in processes involving Ziegler-Nattacatalysts such as those disclosed in U.S. Pat. Nos. 4,076,698 (Andersonet al); 4,950,541 and the patents to which they refer, as well as U.S.Pat. No. 3,645,992 (Elston) as well as those processes utilizingmetallocene and other single site catalysts such as exemplified by U.S.Pat. Nos., 4,937,299 (Ewen et al.), 5,218,071 (Tsutsui et al.),5,278,272, 5,324,800, 5,084,534, 5,405,922, 4,588,794, 5,204,419 and theprocesses subsequently discussed in more detail.

In one embodiment, starting material polyolefins are preferablysubstantially linear ethylene polymers (SLEPs). The substantially linearethylene polymers (SLEPs) are homogeneous polymers having long chainbranching. They are disclosed in U.S. Pat. Nos. 5,272,236 and 5,278,272,the disclosures of which are incorporated herein by reference. SLEPs areavailable as polymers made by the Insite™ Process and CatalystTechnology such as Engage™ polyolefin elastomers (POEs) commerciallyavailable from DuPont Dow Elastomers LLC including Engage™ SM 8400, EG8100, and CL 800. SLEPs can be prepared via the solution, slurry, or gasphase, preferably solution phase, polymerization of ethylene and one ormore optional α-olefin comonomers in the presence of a constrainedgeometry catalyst, such as is disclosed in European Patent Application416,815-A, incorporated herein by reference.

The substantially linear ethylene/α-olefin polymers are made by acontinuous process using suitable constrained geometry catalysts,preferably constrained geometry catalysts as disclosed in U.S.application Ser. Nos.: 545,403, filed Jul. 3, 1990; 758,654, filed Sep.12, 1991; 758,660, filed Sep. 12, 1991; and 720,041, filed Jun. 24,1991, the teachings of all of which are incorporated herein byreference. The monocyclopentadienyl transition metal olefinpolymerization catalysts taught in U.S. Pat. No. 5,026,798, theteachings of which is incorporated herein by reference, are alsosuitable for use in preparing the polymers of the present invention, solong as the reaction conditions are as specified below.

Suitable cocatalysts for use herein include but are not limited to, forexample, polymeric or oligomeric aluminoxanes, especially methylaluminoxane, as well as inert, compatible, noncoordinating, ion formingcompounds. Preferred cocatalysts are inert, noncoordinating, boroncompounds.

The expression “continuous process” means a process in which reactantsare continuously added and product is continuously withdrawn such thatan approximation of a steady state (i.e. substantially constantconcentration of reactants and product while carrying out the process)is achieved. The polymerization conditions for manufacturing thesubstantially linear ethylene/α-olefin polymers of the present inventionare generally those useful in the solution polymerization process,although the application of the present invention is not limitedthereto. Slurry and gas phase polymerization processes are also believedto be useful, provided the proper catalysts and polymerizationconditions are employed.

Multiple reactor polymerization processes can also be used in making thesubstantially linear olefin polymers and copolymers to be rheologicallymodified according to the present invention, such as those disclosed inU.S. Pat. No. 3,914,342, incorporated herein by reference. The multiplereactors can be operated in series or in parallel, with at least oneconstrained geometry catalyst employed in one of the reactors.

The term “substantially linear”, means that, in addition to the shortchain branches attributable to homogeneous comonomer incorporation, theethylene polymer is further characterized as having long chain branchesin that the polymer backbone is substituted with an average of 0.01 to 3long chain branches/1000 carbons. Preferred substantially linearpolymers for use in the invention are substituted with from 0.01 longchain branch/1000 carbons to 1 long chain branch/1000 carbons, and morepreferably from 0.05 long chain branch/1000 carbons to 1 long chainbranch/1000 carbons.

In contrast to the term “substantially linear”, the term “linear” meansthat the polymer lacks measurable or demonstrable long chain branches,i.e., the polymer is substituted with an average of less than 0.01 longchain branch/1000 carbons.

For ethylene/α-olefin interpolymers, “long chain branching” (LCB) meansa chain length longer than the short chain branch that results from theincorporation of the α-olefin(s) into the polymer backbone. Each longchain branch has the same comonomer distribution as the polymer backboneand can be as long as the polymer backbone to which it is attached.

The empirical effect of the presence of long chain branching in thesubstantial linear ethylene/α-olefin interpolymers used in the inventionis manifested in its enhanced rheological properties which arequantified and expressed herein in terms of gas extrusion rheometry(GER) results and/or melt flow, I₁₀/I₂, increases.

The presence of short chain branching of up to 6 carbon atoms in lengthcan be determined in ethylene polymers by using ¹³C nuclear magneticresonance (NMR) spectroscopy and is quantified using the methoddescribed by Randall (Rev. Macromol. Chem. Phys., C.29, V. 2&3, p.285-297), the disclosure of which is incorporated herein by reference.

As a practical matter, current ¹³C nuclear magnetic resonancespectroscopy cannot distinguish the length of a long chain branch inexcess of six carbon atoms. However, there are other known techniquesuseful for determining the presence of long chain branches in ethylenepolymers. Two such methods are gel permeation chromatography coupledwith a low angle laser light scattering detector (GPC-LALLS) and gelpermeation chromatography coupled with a differential viscometerdetector (GPC-DV). The use of these techniques for long chain branchdetection and the underlying theories have been well documented in theliterature. See, e.g., Zimm, G. H. and Stockmayer, W. H., J.Chem. Phys.,17,1301 (1949) and Rudin, A., Modern Methods of PolymerCharacterization, John Wiley & Sons, New York (1991) pp. 103-112, bothof which are incorporated by reference.

A. Willem deGroot and P. Steve Chum, both of The Dow Chemical Company,at the Oct. 4, 1994 conference of the Federation of Analytical Chemistryand Spectroscopy Society (FACSS) in St. Louis, Mo., presented datademonstrating that GPC-DV is a useful technique for quantifying thepresence of long chain branches in SLEPs. In particular, deGroot andChum found that the level of long chain branches in homogeneoussubstantially linear homopolymer samples measured using theZimm-Stockmayer equation correlated well with the level of long chainbranches measured using ¹³C NMR.

Further, deGroot and Chum found that the presence of octene does notchange the hydrodynamic volume of the polyethylene samples in solutionand, as such, one can account for the molecular weight increaseattributable to octene short chain branches by knowing the mole percentoctene in the sample. By deconvoluting the contribution to molecularweight increase attributable to 1-octene short chain branches, deGrootand Chum showed that GPC-DV may be used to quantify the level of longchain branches in substantially linear ethylene/octene copolymers.

deGroot and Chum also showed that a plot of Log (I₂) as a function ofLog (M_(w)) as determined by GPC illustrates that the long chainbranching aspects (but not the extent of long branching) of SLEPs arecomparable to that of high pressure, highly branched low densitypolyethylene (LDPE) and are clearly distinct from ethylene polymersproduced using Ziegler-type catalysts such as titanium complexes andordinary catalysts for making homogeneous polymers such as hafnium andvanadium complexes.

SLEPs are further characterized as having:

(a) a melt flow ratio, I₁₀/I₂≧5.63,

(b) a molecular weight distribution, M_(w)/M_(n) as determined by gelpermeation chromatography and defined by the equation:

(M _(w) /M _(n))≦(I ₁₀ /I ₂)−4.63,

(c) a critical shear stress at the onset of gross melt fracture, asdetermined by gas extrusion rheometry, of greater than 4×10⁶ dynes/cm²or a gas extrusion rheology such that the critical shear rate at onsetof surface melt fracture for the SLEP is at least 50 percent greaterthan the critical shear rate at the onset of surface melt fracture for alinear ethylene polymer, the linear ethylene polymer has an I₂,M_(w)/M_(n) and, preferably density, which are each within ten percentof the SLEP and wherein the respective critical shear rates of the SLEPand the linear ethylene polymer are measured at the same melttemperature using a gas extrusion rheometer, and, preferably,

(d) a single differential scanning calorimetry, DSC, melting peakbetween −30 and 150 C.

For the substantially linear ethylene/α-olefin polymers used in thecompositions of the invention, the I₁₀/I₂ ratio indicates the degree oflong chain branching, i.e., the higher the I₁₀/I₂ ratio, the more longchain branching in the polymer. Generally, the I₁₀/I₂ ratio of thesubstantially linear ethylene/α-olefin polymers is at least about 5.63,preferably at least about 7, especially at least about 8 or above, andas high as about 25.

The melt index for the substantially linear olefin polymers usefulherein is preferably at least about 0.1 grams/10 minutes (g/10 min),more preferably at least about 0.5 g/10 min and especially at leastabout 1 g/10 min up to preferably about 100 g/10 min, more preferably upto about 50 g/10 min, and especially up to about 20 g/10 min.

Determination of the critical shear rate and critical shear stress inregards to melt fracture as well as other rheology properties such asrheological processing index (PI), is performed using a gas extrusionrheometer (GER). The gas extrusion rheometer is described by M. Shida,R. N. Shroff and L. V. Cancio in Polymer Engineering Science, Vol. 17,No. 11, p. 770 (1977), and in Rheometers for Molten Plastics by JohnDealy, published by Van Nostrand Reinhold Co. (1982) on pp. 97-99, bothof which are incorporated by reference herein in their entirety. GERexperiments are generally performed at a temperature of 190 C, atnitrogen pressures between 250 to 5500 psig using a 0.0754 mm diameter,20:1 L/D die with an entrance angle of 180°. For the SLEPs describedherein, the PI is the apparent viscosity (in kpoise) of a materialmeasured by GER at an apparent shear stress of 2.15×10⁶ dyne/cm². TheSLEPs for use in the invention includes ethylene interpolymers and havea PI in the range of 0.01 kpoise to 50 kpoise, preferably 15 kpoise orless. The SLEPs used herein have a PI less than or equal to 70 percentof the PI of a linear ethylene polymer (either a Ziegler polymerizedpolymer or a linear uniformly branched polymer as described by Elston inU.S. Pat. No. 3,645,992) having an I₂, M_(w)/M_(n) and density, eachwithin ten percent of the SLEPs.

The rheological behavior of SLEPs can also be characterized by the DowRheology Index (DRI), which expresses a polymer's “normalized relaxationtime as the result of long chain branching.” (See, S. Lai and G. W.Knight ANTEC ′93 Proceedings, INSITE™ Technology Polyolefins (SLEP)—NewRules in the Structure/Rheology Relationship of Ethylene α-OefinCopolymers, New Orleans, La., May 1993, the disclosure of which isincorporated herein by reference). DRI values range from 0 for polymerswhich do not have any measurable long chain branching (e.g., Tafmer™products available from Mitsui Petrochemical Industries and Exact™products available from Exxon Chemical Company) to about 15 and areindependent of melt index. In general, for low to medium pressureethylene polymers (particularly at lower densities) DRI providesimproved correlations to melt elasticity and high shear flowabilityrelative to correlations of the same attempted with melt flow ratios.For the SLEPs useful in this invention, DRI is preferably at least 0.1,and especially at least 0.5, and most especially at least 0.8. DRI canbe calculated from the equation:

 DRI=(3652879 * τ_(o) ¹ ⁰⁰⁶⁴⁹/η_(o)−1)/10

where τ_(o) is the characteristic relaxation time of the material andη_(o) is the zero shear viscosity of the material. Both τ_(o) and η_(o)are the “best fit” values to the Cross equation, i.e.,

η/η_(o)=1/(1+(γ·τ_(o))^(1-n))

in which n is the power law index of the material, and η and γ are themeasured viscosity and shear rate, respectively. Baseline determinationof viscosity and shear rate data are obtained using a RheometricMechanical Spectrometer (RMS-800) under dynamic sweep mode from 0.1 to100 radians/second at 190 C and a Gas Extrusion Rheometer (GER) atextrusion pressures from 1,000 psi to 5,000 psi (6.89 to 34.5 MPa),which corresponds to shear stress from 0.086 to 0.43 MPa, using a 0.0754mm diameter, 20:1 L/D die at 190 C. Specific material determinations canbe performed from 140 to 190 C as required to accommodate melt indexvariations.

An apparent shear stress versus apparent shear rate plot is used toidentify the melt fracture phenomena and quantify the critical shearrate and critical shear stress of ethylene polymers. According toRamamurthy in the Journal of Rheology, 30(2), 337-357, 1986, thedisclosure of which is incorporated herein by reference, above a certaincritical flow rate, the observed extrudate irregularities may be broadlyclassified into two main types: surface melt fracture and gross meltfracture.

Surface melt fracture occurs under apparently steady flow conditions andranges in detail from loss of specular film gloss to the more severeform of “sharkskin.” Herein, as determined using the above-describedGER, the onset of surface melt fracture (OSMF) is defined as the loss ofextrudate gloss. The loss of extrudate gloss is the point at which thesurface roughness of the extrudate can only be detected by a 40×magnification. The critical shear rate at the onset of surface meltfracture for the SLEPs is at least 50 percent greater than the criticalshear rate at the onset of surface melt fracture of a linear ethylenepolymer having essentially the same I₂ and M_(w)/M_(n).

Gross melt fracture occurs at unsteady extrusion flow conditions andranges in detail from regular (alternating rough and smooth, helical,etc.) to random distortions. For commercial acceptability to maximizethe performance properties of films, coatings and moldings, surfacedefects should be minimal, if not absent. The critical shear stress atthe onset of gross melt fracture for the SLEPs, especially those havinga density >0.910 g/cc, used in the invention is greater than 4×10⁶dynes/cm². The critical shear rate at the onset of surface melt fracture(OSMF) and the onset of gross melt fracture (OGMF) will be used hereinbased on the changes of surface roughness and configurations of theextrudates extruded by a GER.

The SLEPs used in the invention are also characterized by a single DSCmelting peak. The single melting peak is determined using a differentialscanning calorimeter standardized with indium and deionized water. Themethod involves 3-7 mg sample sizes, a “first heat” to about 180° C.which is held for 4 minutes, a cool down at 10° C./min. to −30° C. whichis held for 3 minutes, and heat up at 10° C./min. to 140° C. for the“second heat”. The single melting peak is taken from the “second heat”heat flow vs. temperature curve. Total heat of fusion of the polymer iscalculated from the area under the curve.

For polymers having a density of 0.875 g/cc to 0.910 g/cc, the singlemelting peak may show, depending on equipment sensitivity, a “shoulderor a “hump” on the low melting side that constitutes less than 12percent, typically, less than 9 percent, and more typically less than 6percent of the total heat of fusion of the polymer. Such an artifact isobservable for other homogeneously branched polymers such as Exact™resins and is discerned on the basis of the slope of the single meltingpeak varying monotonically through the melting region of the artifact.Such an artifact occurs within 34° C., typically within 27° C., and moretypically within 20° C. of the melting point of the single melting peak.The heat of fusion attributable to an artifact can be separatelydetermined by specific integration of its associated area under the heatflow vs. temperature curve.

The molecular weight distributions of ethylene α-olefin polymers aredetermined by gel permeation chromatography (GPC) on a Waters 150C hightemperature chromatographic unit equipped with a differentialrefractometer and three columns of mixed porosity. The columns aresupplied by Polymer Laboratories and are commonly packed with pore sizesof 10³, 10⁴, 10⁵ and 10⁶ Å (10⁻⁴, 10⁻³, 10⁻² and 10⁻¹ mm). The solventis 1,2,4-trichlorobenzene, from which about 0.3 percent by weightsolutions of the samples are prepared for injection. The flow rate isabout 1.0 milliliters/minute, unit operating temperature is about 140°C. and the injection size is about 100 microliters.

The molecular weight determination with respect to the polymer backboneis deduced by using narrow molecular weight distribution polystyrenestandards (from Polymer Laboratories) in conjunction with their elutionvolumes. The equivalent polyethylene molecular weights are determined byusing appropriate Mark-Houwink coefficients for polyethylene andpolystyrene (as described by Williams and Ward in Journal of PolymerScience, Polymer Letters, Vol. 6, p. 621, 1968) to derive the followingequation:

M_(polyethylene)=a * (M_(polystyrene))^(b).

In this equation, a=0.4316 and b=1.0. Weight average molecular weight,M_(w), is calculated in the usual manner according to the followingformula: Mj=(Σ w_(i) (M_(i) ^(j)))^(j); where w_(i) is the weightfraction of the molecules with molecular weight M_(i) eluting from theGPC column in fraction i and j=1 when calculating M_(w) and j=−1 whencalculating M_(n).

The density of the linear or the substantially linear ethylene polymers(as measured in accordance with ASTM D-792) for use in the presentinvention is generally less than about 0.90 g/cm³. The density ispreferably at least about 0.85 g/cm³ and preferably up to about 0.90g/cm³, more preferably up to about 0.88 g/cm³. The most preferreddensity is determined primarily by the modulus of elasticity orflexibility desired in for instance, a resulting molded article. Thedensity advantageously remains substantially constant during rheologymodification according to this invention.

The most preferred polymers as starting materials for this invention areethylene copolymers with narrow MWD (that is a Mw/Mn of less than 3.5most preferably less than about 2.5). These can be produced using atleast one C3-C20 olefin comonomer. Most preferred for copolymer isC3-C10. About 3-30 mole percent comonomer as determined by ASTM 5017 ispreferred in the starting material. The preferred melt index of thestarting material is at least about 0.2, preferably up to about 20 g/20min, or it preferably has Mooney viscosity of at least about 5, morepreferably up to about 50 Mooney (as measured by ASTM D 1646-92 at 25°C.) run time of 9 minutes, 38.1 mm diameter rotor, rotor speed of 0.2rad/sec. Commercially available polymers in this category include NORDELand ENGAGE polyolefin elastomers commercially available from DuPont-DowElastomers and VISTALON elastomers commercially available from ExxonChemicals. For elastomeric applications, the preferred comonomer contentis between about 20-40 weight percent. The most preferred terpolymer isan EPDM such as NORDEL ethylene/propylene/diene polymer commerciallyavailable from DuPont-Dow Elastomers.

The melt index is measured according to ASTM D-1238 condition 190°C./2.16 Kg(formerly known as Condition E).

For the purposes of rheology modification or coupling, the polymer isreacted with a polyfunctional compound capable of insertion reactionsinto C—H bonds. Such polyfunctional compounds have at least two,preferably 2, functional groups capable of C—H insertion reactions.Those skilled in the art are familiar with C—H insertion reactions andfunctional groups capable of such reactions. For instance, carbenes asgenerated from diazo compounds, as cited in Mathur, N. C.; Snow, M. S.;Young, K. M., and Pincock, J. A.; Tetrahedron, (1985), 41(8), pages1509-1516, and nitrenes as generated from azides, as cited inAbramovitch, R. A.,; Chellathurai, T.; Holcomb, W. D; McMaster, I. T.;and Vanderpool, D. P.; J. Org. Chem., (1977), 42(17), 2920-6, andAbramovitch, R. A., Knaus, G. N., J. Org. Chem., (1975), 40(7), 883-9.

Compounds having at least two functional groups capable of C—H insertionunder reaction conditions are referred to herein as coupling agents.Such coupling agents include alkyl and aryl azides (R—N₃), acyl azides(R—C(O)N₃), azidoformates (R—O—C(O)—N₃), phosphoryl azides((RO)₂—(PO)—N₃), phosphinic azides (R₂—P(O)—N₃)and silyl azides(R₃—Si—N₃).

Polyfunctional compounds capable of insertions into C—H bonds alsoinclude poly(sulfonyl azide)s. The poly(sulfonyl azide) is any compoundhaving at least two sulfonyl azide groups (—SO₂N₃) reactive with thepolyolefin. Preferably the poly(sulfonyl azide)s have a structure X—R—Xwherein each X is SO₂N₃ and R represents an unsubstituted or inertlysubstituted hydrocarbyl, hydrocarbyl ether or silicon-containing group,preferably having sufficient carbon, oxygen or silicon, preferablycarbon, atoms to separate the sulfonyl azide groups sufficiently topermit a facile reaction between the polyolefin and the sulfonyl azide,more preferably at least 1, more preferably at least 2, most preferablyat least 3 carbon, oxygen or silicon, preferably carbon, atoms betweenfunctional groups. While there is no critical limit to the length of R,each R advantageously has at least one carbon or silicon atom betweenX's and preferably has less than about 50, more preferably less thanabout 30, most preferably less than about 20 carbon, oxygen or siliconatoms. Within these limits, larger is better for reasons includingthermal and shock stability. When R is straight-chain alkyl hydrocarbon,there are preferably less than 4 carbon atoms between the sulfonyl azidegroups to reduce the propensity of the nitrene to bend back and reactwith itself. Silicon containing groups include silanes and siloxanes,preferably siloxanes. The term inertly substituted refers tosubstitution with atoms or groups which do not undesirably interferewith the desired reaction(s) or desired properties of the resultingcoupled polymers. Such groups include fluorine, aliphatic or aromaticether, siloxane as well as sulfonyl azide groups when more than twopolyolefin chains are to be joined. Suitable structures include R asaryl, alkyl, aryl alkaryl, arylalkyl silane, siloxane or heterocyclic,groups and other groups which are inert and separate the sulfonyl azidegroups as described. More preferably R includes at least one aryl groupbetween the sulfonyl groups, most preferably at least two aryl groups(such as when R is 4,4′ diphenylether or 4,4′-biphenyl). When R is onearyl group, it is preferred that the group have more than one ring, asin the case of naphthylene bis(sulfonyl azides). Poly(sulfonyl)azidesinclude such compounds as 1,5-pentane bis(sulfonlazide), 1,8-octanebis(sulfonyl azide), 1,10-decane bis(sulfonyl azide), 1,10-octadecanebis(sulfonyl azide), 1-octyl-2,4,6-benzene tris(sulfonyl azide),4,4′-diphenyl ether bis(sulfonyl azide),1,6-bis(4′-sulfonazidophenyl)hexane, 2,7-naphthalene bis(sulfonylazide), and mixed sulfonyl azides of chlorinated aliphatic hydrocarbonscontaining an average of from 1 to 8 chlorine atoms and from about 2 to5 sulfonyl azide groups per molecule, and mixtures thereof. Preferredpoly(sulfonyl azide)s include oxy-bis(4-sulfonylazidobenzene),2,7-naphthalene bis(sulfonyl azido), 4,4′-bis(sulfonyl azido)biphenyl,4,4′-diphenyl ether bis(sulfonyl azide) and bis(4-sulfonylazidophenyl)methane, and mixtures thereof.

Sulfonyl azides are conveniently prepared by the reaction of sodiumazide with the corresponding sulfonyl chloride, although oxidation ofsulfonyl hydazines with various reagents (nitrous acid, dinitrogentetroxide, nitrosonium tetrafluoroborate) has been used.

Polyfunctional compounds capable of insertions into C—H bonds alsoinclude carbene-forming compounds such as salts of alkyl and arylhydrazones and diazo compounds, and nitrene-forming compounds such asalkyl and aryl azides (R—N₃), acyl azides (R—C(O)N₃), azidoformates(R—O—C(O)—N₃), sulfonyl azides (R—SO₂—N₃), phosphoryl azides((RO)₂—(PO)—N₃), phosphinic azides (R₂—P(O)—N₃) and silyl azides(R₃—Si—N₃). Some of the coupling agents of the invention are preferredbecause of their propensity to form a greater abundance ofcarbon-hydrogen insertion products. Such compounds as the salts ofhydrazones, diazo compounds, azidoformates, sulfonyl azides, phosphorylazides, and silyl azides are preferred because they form stablesinglet-state electron products (carbenes and nitrenes) which carry outefficient carbon-hydrogen insertion reactions, rather thansubstantially 1) rearranging via such mechanisms as the Curtius-typerearrangement, as is the case with acyl azides and phosphinic azides, or2) rapidly converting to the triplet-state electron configuration whichpreferentially undergoes hydrogen atom abstraction reactions, which isthe case with alkyl and aryl azides. Also, selection from among thepreferred coupling agents is conveniently possible because of thedifferences in the temperatures at which the different classes ofcoupling agents are converted to the active carbene or nitrene products.For example, those skilled in the art will recognize that carbenes areformed from diazo compounds efficiently at temperatures less than 100°C., while salts of hydrazones, azidoformates and the sulfonyl azidecompounds react at a convenient rate at temperatures above 100° C., upto temperatures of about 200° C. (By convenient rates it is meant thatthe compounds react at a rate that is fast enough to make commercialprocessing possible, while reacting slowly enough to allow adequatemixing and compounding to result in a final product with the couplingagent adequately dispersed and located substantially in the desiredposition in the final product. Such location and dispersion may bedifferent from product to product depending on the desired properties ofthe final product.) Phosphoryl azides may be reacted at temperatures inexcess of 180° C. up to about 300° C., while silyl azides reactpreferentially at temperatures of from about 250° C. to 400° C.

To modify rheology, also referred to herein as “to couple,” thepoly(sulfonyl azide) is used in a rheology modifying amount, that is anamount effective to increase the low-shear viscosity (at 0.1 rad/sec) ofthe polymer preferably at least about 5 percent as compared with thestarting material polymer, but less than a crosslinking amount, that isan amount sufficient to result in at least about 10 weight percent gelas measured by ASTM D2765-procedure A. While those skilled in the artwill recognize that the amount of azide sufficient to increase the lowshear viscosity and result in less than about 10 weight percent gel willdepend on molecular weight of the azide used and polymer the amount ispreferably less than about 5 percent, more preferably less than about 2percent, most preferably less than about 1 weight percent poly(sulfonylazide) based on total weight of polymer when the poly(sulfonyl azide)has a molecular weight of from about 200 to about 2000. To achievemeasurable rheology modification, the amount of poly(sulfonyl azide) ispreferably at least about 0.01 weight percent, more preferably at leastabout 0.05 weight percent, most preferably at least about 0.10 weightpercent based on total polymer.

For rheology modification, the sulfonyl azide is admixed with thepolymer and heated to at least the decomposition temperature of thesulfonyl azide. By decomposition temperature of the azide it is meantthat temperature at which the azide converts to the sulfonyl nitrene,eliminating nitrogen and heat in the process, as determined bydifferential scanning calorimetry (DSC). The poly(sulfonyl azide) beginsto react at a kinetically significant rate (convenient for use in thepractice of the invention) at temperatures of about 130° C. and isalmost completely reacted at about 160° C. in a DSC (scanning at 10°C./min). ARC (scanning at 2° C./hr) shows onset of decomposition isabout 100° C. Extent of reaction is a function of time and temperature.At the low levels of azide used in the practice of the invention, theoptimal properties are not reached until the azide is essentially fullyreacted. Temperatures for use in the practice of the invention are alsodetermined by the softening or melt temperatures of the polymer startingmaterials. For these reasons, the temperature is advantageously greaterthan about 90° C., preferably greater than about 120° C., morepreferably greater than about 150° C., most preferably greater than 180°C.

Preferred times at the desired decomposition temperatures are times thatare sufficient to result in reaction of the coupling agent with thepolymer(s) without undesirable thermal degradation of the polymermatrix. Preferred reaction times in terms of the half life of thecoupling agent, that is the time required for about half of the agent tobe reacted at a preselected temperature, which half life is determinableby DSC is about 5 half lives of the coupling agent. In the case of abis(sulfonyl azide), for instance, the reaction time is preferably atleast about 4 minutes at 200° C.

Admixing of the polymer and coupling agent is conveniently accomplishedby any means within the skill in the art. Desired distribution isdifferent in many cases, depending on what rheological properties are tobe modified. In a homopolymer it is desirable to have as homogeneous adistribution as possible, preferably achieving solubility of the azidein the polymer melt. In a blend it is desirable to have low solubilityin one or more of the polymer matrices such that the azide ispreferentially in one or the other phase, or predominantly in theinterfacial region between the two phases

Preferred processes include at least one of (a) dry blending thecoupling agent with the polymer, preferably to form a substantiallyuniform admixture and adding this mixture to melt processing equipment,e.g. a melt extruder to achieve the coupling reaction, at a temperatureat least the decomposition temperature of the coupling agent; (b)introducing, e.g. by injection, a coupling agent in liquid form, e.g.dissolved in a solvent therefor or in a slurry of coupling agent in aliquid, into a device containing polymer, preferably softened, molten ormelted polymer, but alternatively in particulate form, in solution ordispersion, more preferably in melt processing equipment; (c) forming afirst admixture of a first amount of a first polymer and a couplingagent, advantageously at a temperature less than about the decompositiontemperature of the coupling agent, preferably by melt blending, and thenforming a second admixture of the first admixture with a second amountof a second polymer (for example a concentrate of a coupling agentadmixed with at least one polymer and optionally other additives, isconveniently admixed into a second polymer or combination thereofoptionally with other additives, to modify the second polymer(s)); (d)feeding at least one coupling agent, preferably in solid form, morepreferably finely comminuted, e.g. powder, directly into softened ormolten polymer, e.g. in melt processing equipment, e.g. in an extruder;or combinations thereof. Among processes (a) through (d), processes (b)and (c) are preferred, with (c) most preferred. For example, process (c)is conveniently used to make a concentrate with a first polymercomposition having a lower melting temperature, advantageously at atemperature below the decomposition temperature of the coupling agent,and the concentrate is melt blended into a second polymer compositionhaving a higher melting temperature to complete the coupling reaction.Concentrates are especially preferred when temperatures are sufficientlyhigh to result in loss of coupling agent by evaporation or decompositionnot leading to reaction with the polymer, or other conditions wouldresult that effect. Alternatively, some coupling occurs during theblending of the first polymer and coupling agent, but some of thecoupling agent remains unreacted until the concentrate is blended intothe second polymer composition. Each polymer or polymer compositionincludes at least one homopolymer, copolymer, terpolymer, orinterpolymer and optionally includes additives within the skill in theart. When the coupling agent is added in a dry form it is preferred tomix the agent and polymer in a softened or molten state below thedecomposition temperature of the coupling agent then to heat theresulting admixture to a temperature at least equal to the decompositiontemperature of the coupling agent.

The term “melt processing” is used to mean any process in which thepolymer is softened or melted, such as extrusion, pelletizing, molding,thermoforming, film blowing, compounding in polymer melt form, fiberspinning, and the like.

The polyolefin(s) and coupling agent are suitably combined in any mannerwhich results in desired reaction thereof, preferably by mixing thecoupling agent with the polymer(s) under conditions which allowsufficient mixing before reaction to avoid uneven amounts of localizedreaction then subjecting the resulting admixture to heat sufficient forreaction. Preferably, a substantially uniform admixture of couplingagent and polymer is formed before exposure to conditions in which chaincoupling takes place. A substantially uniform admixture is one in whichthe distribution of coupling agent in the polymer is sufficientlyhomogeneous to be evidenced by a polymer having a melt viscosity aftertreatment according to the practice of the invention either higher atlow angular frequency (e.g. 0.1 rad/sec) or lower at higher angularfrequency (e.g. 100 rad/sec) than that of the same polymer which has notbeen treated with the coupling agent but has been subjected to the sameshear and thermal history. Thus, preferably, in the practice of theinvention, decomposition of the coupling agent occurs after mixingsufficient to result in a substantially uniform admixture of couplingagent and polymer. This mixing is preferably attained with the polymerin a molten or melted state, that is above the crystalline melttemperature, or in a dissolved or finely dispersed condition rather thanin a solid mass or particulate form. The molten or melted form is morepreferred to insure homogeniety rather than localized concentrations atthe surface.

Any equipment is suitably used, preferably equipment which providessufficient mixing and temperature control in the same equipment, butadvantageously practice of the invention takes place in such devices asan extruder or a static polymer mixing devise such as a Brabenderblender. The term extruder is used for its broadest meaning to includesuch devices as a device which extrudes pellets or pelletizer.Conveniently, when there is a melt extrusion step between production ofthe polymer and its use, at least one step of the process of theinvention takes place in the melt extrusion step. While it is within thescope of the invention that the reaction take place in a solvent orother medium, it is preferred that the reaction be in a bulk phase toavoid later steps for removal of the solvent or other medium. For thispurpose, a polymer above the crystalline melt temperature isadvantageous for even mixing and for reaching a reaction temperature(the decomposition temperature of the sulfonyl azide).

In a preferred embodiment the process of the present invention takesplace in a single vessel, that is mixing of the coupling agent andpolymer takes place in the same vessel as heating to the decompositiontemperature of the coupling agent. The vessel is preferably a twin-screwextruder, but is also advantageously a single-screw extruder or a batchmixer. The reaction vessel more preferably has at least two zones ofdifferent temperatures into which a reaction mixture would pass, thefirst zone advantageously being at a temperature at least thecrystalline melt temperature or the softening temperature of thepolymer(s) and preferably less than the decomposition temperature of thecoupling agents and the second zone being at a temperature sufficientfor decomposition of the coupling agent. The first zone is preferably ata temperature sufficiently high to soften the polymer and allow it tocombine with the coupling agent through distributive mixing to asubstantially uniform admixture.

For polymers that have softening points above the coupling agentdecomposition temperature (preferably greater than 200° C.), andespecially when incorporation of a lower melting polymer (such as in aconcentrate) is undesirable, the preferred embodiment for incorporationof coupling agent is to solution blend the coupling agent in solution oradmixture into the polymer, to allow the polymer to imbibe (absorb oradsorb at least some of the coupling agent), and then to evaporate thesolvent. After evaporation, the resulting mixture is extruded. Thesolvent is preferably a solvent for the coupling agent, and morepreferably also for the polymer when the polymer is soluble such as inthe case of polycarbonate. Such solvents include polar solvents such asacetone, THF (tetrahydrofuran) and chlorinated hydrocarbons such asmethylene chloride. Alternatively other non-polar compounds such asmineral oils in which the coupling agent is sufficiently miscible todisperse the coupling agent in a polymer, are used.

To avoid the extra step and resultant cost of re-extrusion and to insurethat the coupling agent is well blended into the polymer, in alternativepreferred embodiments it is preferred that the coupling agent be addedto the post-reactor area of a polymer processing plant. For example, ina slurry process of producing polyethylene, the coupling agent is addedin either powder or liquid form to the powdered polyethylene after thesolvent is removed by decantation and prior to the drying anddensification extrusion process. In an alternative embodiment, whenpolymers are prepared, in a gas phase process, the coupling agent ispreferably added in either powder or liquid form to the powderedpolyethylene before the densification extrusion. In an alternativeembodiment when a polymer is made in a solution process, the couplingagent is preferably added to the polymer solution prior to thedensification extrusion process.

Practice of the process of the invention to rheology modify elastomersyields rheology modified or chain coupled elastomers, that is thepolymers which have sulfonamide, amine, alkyl-substituted oraryl-substituted carboxamide, alkyl-substituted or aryl-substitutedphosphoramide, alkyl-substituted or aryl-substituted methylene couplingbetween different polymer chains. Resulting elastomers advantageouslyshow higher low shear viscosity than the original polymer due tocoupling of long polymer chains to polymer backbones. Broad molecularweight distribution polymers (polydispersity (P.D.) of 3.5 and greater)and gel levels less than 2 percent as determined by xylene extractionshow less improvement than the dramatic effect noted in narrow MWDpolymer (P.D.=2.0) with gel less than 2 percent as determined by xyleneextraction.

Rheology modification leads to polymers which have controlledrheological properties, specifically improved melt strength as evidencedby increased low shear viscosity, better ability to hold oil, improvedscratch and mar resistance, improved tackiness, improved green strength(melt), higher orientation in high shear and high extensional processessuch as injection molding, film extrusion (blown and cast), calendaring,fiber production, profile extrusion, foams, and wire & cable insulationas measured by tan delta as described hereinafter, elastic viscosity at0.1 rad/sec and 100 rad/sec, respectively. It is also believed that thisprocess can be used to produce dispersions having improved properties ofhigher low shear viscosity than the unmodified polymer as measured byDMS.

Rheology modified elastomers are useful as large blow-molded articlesdue to the higher low shear viscosity than unmodified polymer and themaintenance of the high shear viscosity for processability as indicatedby high shear viscosity, foams for stable cell structure as measured bylow shear viscosity, elastic film for better bubble stability asmeasured by low shear viscosity, elastic fibers for better spinnabilityas measured by high shear viscosity, cable and wire insulation for greenstrength to avoid sagging or deformation of the polymer on the wire asmeasured by low shear viscosity which are aspects of the invention.

Elastomers rheology modified according to the practice of the inventionare superior to the corresponding unmodified polymer starting materialsfor these applications due to the elevation of viscosity, of preferablyat least about 5 percent at low shear rates (0.1 rad/sec), sufficientlyhigh melt strengths to avoid deformation during thermal processing (e.g.to avoid sag during thermoforming) or to achieve bubble strength duringblow molding, and sufficiently low high shear rate viscosities tofacilitate molding and extrusion. These rheological attributes enablefaster filling of injection molds at high rates than the unmodifiedstarting materials, the setup of foams (stable cell structure)asindicated by formation of lower density closed cell foam, preferablywith higher tensile strength, insulation properties, and/or compressionset than attained in the use of coupling or rheology modification usingcoupling agents which generate free radicals, because of high meltviscosity . Advantageously toughness and tensile strength of thestarting material is maintained.

Polymers resulting from the practice of the invention are different fromthose resulting from practice of prior art processes as shown in CA797,917. The polymers of the present invention show improved meltelasticity, that is higher tan delta as measured by DMS, betterdrawability, that is higher melt strength as measured by melt tension,than the unmodified polymer counterpart in thermoforming and large partblow molding.

There are many types of molding operations which can be used to formuseful fabricated articles or parts from the formulations disclosedherein, including various injection molding processes (e.g., thatdescribed in Modern Plastics Encyclopedia/89, Mid October 1988 Issue,Volume 65, Number 11, pp. 264-268, “Introduction to Injection Molding”and on pp. 270-271, “Injection Molding Thermoplastics”, the disclosuresof which are incorporated herein by reference) and blow moldingprocesses (e.g., that described in Modern Plastics Encyclopedia/89, MidOctober 1988 Issue, Volume 65, Number 11, pp. 217-218, “Extrusion-BlowMolding”, the disclosure of which is incorporated herein by reference),profile extrusion, calendering, pultrusion and the like.

The rheology-modified ethylene polymers, processes for making them, andintermediates for making them of this invention are useful in theautomotive area, industrial goods, building and construction, electrical(e.g., wire and cable coatings/insulation) and tire products. Some ofthe fabricated articles include automotive hoses, tubing, and sheet (forinstance, skins for instrument panel, car door and seat), single plyroofing, and wire and cable voltage insulation and jackets. In thermosetelastomer applications, the elastomer is traditionally first fabricatedinto a part, and then the resulting part is crosslinked. Practice of theinvention provides enhanced melt strength to the resin such that it canbe shaped or fabricated into parts advantageously substantially withoutsevere deformation due to low melt strength. For example, in wire andcable applications, enhanced melt strength polymers allow the wire to bemore effectively coated without the coating sagging with the resultingthickness variation around the circumference of the cable. The effect ofimproved melt strength is also applicable to profile extrusions wherethe enhanced melt strength is advantageous to forming a uniform diameterfor tubing or uniform thickness for gaskets and seals.

Elastic film and film structures particularly benefit from thisinvention and can be made using conventional blown film fabricationtechniques or other biaxial orientation processes such as tenter framesor double bubble processes. Conventional blown film processes aredescribed, for example, in The Encyclopedia of Chemical Technology,Kirk-Othmer, Third Edition, John Wiley & Sons, New York, 1981, vol. 16,pp. 416-417 and Vol. 18, pp. 191-192. Biaxial orientation filmmanufacturing process such as described in a “double bubble” process asin U.S. Pat. No. 3,456,044 (Pahlke), and the processes described in U.S.Pat. No. 4,352,849 (Mueller), U.S. Pat. No. 4,597,920 (Golike), U.S.Pat. No. 4,820,557 (Warren), U.S. Pat. No. 4,837,084 (Warren), U.S. Pat.No. 4,865,902 (Golike et al.), U.S. Pat. No. 4,927,708 (Herran et al.),U.S. Pat. No. 4,952,451 (Mueller), U.S. Pat. No. 4,963,419 (Lustig etal.), and U.S. Pat. No. 5,059,481 (Lustig et al.), can also be used tomake film structures from the novel compositions described herein. Thefilm structures can also be made as described in a tenter-frametechnique, such as that used for oriented polypropylene.

Other multi-layer elastic film manufacturing techniques for foodpackaging applications are described in Packaging Foods With Plastics,by Wilmer A. Jenkins and James P. Harrington (1991), pp. 19-27, and in“Coextrusion Basics” by Thomas I. Butler, Film Extrusion Manual:Process, Materials, Properties pp. 31-80 (published by the TAPPI Press(1992)).

The elastic films may be monolayer or multilayer films. The film madeusing this invention can also be coextruded with the other layer(s) orthe film can be laminated onto another layer(s) in a secondaryoperation, such as that described in Packaging Foods With Plastics, byWilmer A. Jenkins and James P. Harrington (1991) or that described in“Coextrusion For Barrier Packaging” by W. J. Schrenk and C. R. Finch,Society of Plastics Engineers RETEC Proceedings, Jun. 15-17 (1981), pp.211-229. If a monolayer film is produced via tubular film (i.e., blownfilm techniques) or flat die (i.e., cast film) as described by K. R.Osborn and W. A. Jenkins in “Plastic Films, Technology and PackagingApplications” (Technomic Publishing Co., Inc., 1992), the disclosure ofwhich is incorporated herein by reference, then the film must go throughan additional post-extrusion step of adhesive or extrusion lamination toother packaging material layers to form a multilayer structure. If thefilm is a coextrusion of two or more layers (also described by Osbornand Jenkins), the film may still be laminated to additional layers ofpackaging materials, depending on the other physical requirements of thefinal film. “Laminations vs. Coextrusion” by D. Dumbleton (ConvertingMagazine (September 1992), also discusses lamination versus coextrusion.Monolayer and coextruded films can also go through other post extrusiontechniques, such as a biaxial orientation process.

Extrusion coating is yet another technique for producing multilayer filmstructures using the novel compositions described herein. The novelcompositions comprise at least one layer of the film structure. Similarto cast film, extrusion coating is a flat die technique. A sealant canbe extrusion coated onto a substrate either in the form of a monolayeror a coextruded extrudate.

Generally for a multilayer film structure, the novel compositionsdescribed herein comprise at least one layer of the total multilayerfilm structure. Other layers of the multilayer structure include but arenot limited to barrier layers, and/or tie layers, and/or structurallayers. Various materials can be used for these layers, with some ofthem being used as more than one layer in the same film structure. Someof these materials include: foil, nylon, ethylene/vinyl alcohol (EVOH)copolymers, polyvinylidene chloride (PVDC), polyethylene terethphalate(PET), oriented polypropylene (OPP), ethylene/vinyl acetate (EVA)copolymers, ethylene/acrylic acid (EAA) copolymers, ethylene/methacrylicacid (EMAA) copolymers, LLDPE, HDPE, LDPE, nylon, graft adhesivepolymers (e.g., maleic anhydride grafted polyethylene), and paper.Generally, the multilayer film structures comprise from 2 to 7 layers.

The rheology modified elastomer can be used to extrusion coat onto awoven polypropylene or woven high density polyethylene scrim for tarpapplications.

Such articles comprising the rheology-modified polymer of this inventionmay be made by melt processing the rheology-modified elastomer accordingto this invention. That process may include processing pellets orgranules of polymer which have been rheology-modified according to thisinvention. In a preferred embodiment, the pellets or granules aresubstantially free of unreacted crosslinking agent when the crosslinkingagent comprises a heat-activated crosslinking agent.

Articles prepared from the rheology modified elastomers are optionallyand advantageously crosslinked subsequent to shaping (fabrication).Crosslinking before fabrication often results in localized gels thatundesirably introduce flaws. Flaws are sometimes visible or can reducesuch characteristics as tensile properties or toughness of the finalarticle, crosslinking after fabrication. Introduced in a step subsequentto fabrication, crosslinking is advantageously distributed evenly in theresulting article so that the reduction in tensile properties isminimized. Crosslinking in a subsequent step is optionally accomplishedusing any means within the skill in the art, for instance radiation,including e-beam radiation, or heat. In the case crosslinking by heat,peroxide, azide and other crosslinking agents are conveniently addedbefore the article is fabricated and the fabrication temperature isdesirably lower than the decomposition of the crosslinking agent. Onemeans within the skill in the art for achieving a sufficiently lowfabrication temperature is adding oil to the resin to reduce theviscosity. The crosslinked article advantageously has lower compressionset as measured by ASTM D 395-89 than the article prior to crosslinking.Such articles are optionally and alternatively made by melt processingan intermediate composition comprising a rheology modified elastomer ofthe invention which contains unreacted crosslinking agent. Thecrosslinking agent is optionally included in a composition including thepoly(sulfonyl azide) before the decomposition temperature of thepoly(sulfonyl azide) is reached or alternatively added after coupling.If the crosslinking agent is added before the decomposition temperatureof the poly(sulfonyl azide) is reached, then the crosslinking agentshould be insufficiently reactive under coupling conditions to causesufficient crosslinking to introduce detrimental amounts of localizedgels (Those skilled in the art will recognize that the amounts of gelwhich are detrimental vary with the final article to be produced.) Insuch a case the crosslinking agent is conveniently activated at a highertemperature or by different conditions than are occur in coupling. Morepreferably, crosslinking agent is added to coupled elastomer or thefabricated article is exposed to radiation. In another embodiment, anamount of poly(sulfonyl azide) sufficient for coupling and latercrosslinking is used in a composition and exposed to sufficient heat fora sufficient time to couple the elastomer but to form less than about 2weight percent gel, then the composition is fabricated into an article,after which the article is heated to decompose sufficient poly(sulfonylazide) to result in crosslinking. Oils, plasticizers, fillers,colorants, and antioxidants are optionally added to the rheologymodified elastomers during the article fabrication process. Examples ofthe use of rheology modified elastomers in crosslinked elastomerapplications include gaskets, wire and cable coatings, roofingmembranes, foams, weather stripping, hoses and the like where the partsadvantageously have low compression set and elevated servicetemperature.

The rheology-modified polymers and intermediates used to makerheology-modified polymers may be used alone or in combination with oneor more additional polymers in a polymer blend. When additional polymersare present, they may be selected from any of the modified or unmodifiedhomogeneous polymers described above for this invention and/or anymodified or unmodified heterogeneous polymers.

Compositions of the invention and compositions produced by practice ofthe invention are particularly useful because of their surprisingproperties. The low density ethylene copolymer preferred embodiments(density less than about 0.89 g/mL and comonomer content preferablyabout 5-25 mole percent) are particularly useful in extrusion such as toform wire and cable coatings, tubing, profiles such as gaskets andseals, sheeting, extrusion coatings such as carpet backing, multilayerpackaging, tougheners, and impact modifiers for blends of polymers,preferably for wire and cable coating, tougheners and impact modifiers.The low density preferred embodiments are also particularly useful forcalendaring to form such materials as sheeting, packaging films, andnon-packaging films; for foams particularly cushion packaging, toys,building and construction uses, automotive uses, such as overhead andinsulation foams, body boards, airline seats, floral and craft uses,preferably cushion packaging, building and construction, automotiveuses, and body boards; and for adhesives and sealants, particularly hotmelt adhesives, pressure sensitive adhesives (whether applied insolvents or by hot melt), caulks, and as tackifiers in othercompositions.

The following examples are to illustrate this invention and do not limitit. Ratios, parts, and percentages are by weight unless otherwisestated. Examples (Ex) of the invention are designated numerically whilecomparative samples (C.S.) are designated alphabetically and are notexamples of the invention.

Test Methods

A Rheometrics, Inc. RMS-800 dynamic mechanical spectrometer (DMS) with25 mm diameter parallel plates was used to determine the dynamicrheological data. A frequency sweep with five logarithmically spacedpoints per decade was run from 0.1 to 100 rad/s at 190° C. The strainwas determined to be within the linear viscoelastic regime by performinga strain sweep at 0.1 rad/s and 190° C., by strain sweep from 2 to 30percent strain in 2 percent steps to determine the minimum requiredstrain to produce torques within the specification of the transducer;another strain sweep at 100 rad/s and 190° C. was used to determine themaximum strain before nonlinearity occurred according to the proceduredisclosed by J. M. Dealy and K. F. Wissbrun, “Melt Rheology and Its Rolein Plastics Processing”, Van Nostrand, N.Y. (1990). All testing wasperformed in a nitrogen purge to minimize oxidative degradation.

Xylene Extraction was performed by weighing out 1 gram samples ofpolymer. The samples are transferred to a mesh basket which is thenplaced in boiling xylene for 12 hours. After 12 hours, the samplebaskets are removed and placed in a vacuum oven at 150° C. and 28 in. ofHg vacuum for 12 hours. After 12 hours, the samples are removed, allowedto cool to room temperature over a 1 hour period, and then weighed. Theresults are reported as percent polymer extracted. Percentextracted=(initial weight-final weight)/initial weight according to ASTMD-2765 Procedure “A”.

Samples were prepared using a HaakeBuchler Rheomix 600 mixer with rollerstyle blades, attached to a HaakeBuchler Rheocord 9000 Torque rheometer.

All instruments were used according to manufacturer's directions.

EXAMPLES 1 AND 2 AND COMPARATIVE SAMPLE A

A 43 g sample of an ethylene (69 weight percent) propylene (30.5 weightpercent) 5-ethylidene-2-norbornene(ENB) (0.5 weight percent)terpolymerwith specific gravity 0.88, Mooney viscosity 20 (by ASTM D 1646-92)Mw/Mn=3.86 and Mw=146,200 commercially available from DuPont DowElastomers LLC under the trade designation Nordel IP NDR 3720hydrocarbon rubber (containing 1000 ppm hindered polyphenolic stabilizercommercially available from Ciba Geigy Corporation under the tradedesignation Irganox 1076 stabilizers) was mixed in a Haake mixer. Thepolymer was prepared using a constrained geometry catalyst. The polymerwas melted at 100° C. for 2 minutes until all pellets were molten. Then0.05 weight percent of 4,4′-oxybis(benzenesulfonyl azide) CAS#[7456-68-0] was mixed into the molten polymer for 2 minutes. Afterintimate mixing was achieved, the temperature was adjusted to 170° C.and the rotational speed was increased from 20 to 40 rpm over a periodof 7 minutes to reach a maximum of 180° C. The mixture is held at thishigher temperature and high rotational speed for 12 minutes, and then itwas cooled to 150° C. The sample was removed from the Haake and allowedto cool to room temperature.

For Example 2 the procedure of Example 1 was repeated but using 0.1weight percent 4,4′-oxybis(benzenesulfonyl azide). Comparative Sample Awas the same starting material not treated with poly(sulfonyl azide).

Rheological properties (viscosity and tan delta) were measured for eachsample plus an unmodified control (Comparative Sample A) at 190° C. overa frequency range of 0.1 to 100 rad/second using a Rheometricsmechanical spectrometer equipped with parallel 25 mm diameter platesaccording to manufactures directions. The low shear viscosity is theviscosity measured at the lowest frequency. The high shear viscosity wasdetermined by DMS at 100 rad/sec.

The results of these tests are in Table 1.

EXAMPLES 3 AND 4 AND COMPARATIVE SAMPLE B

The procedure of Example 1 is repeated using an ethylene (72 weightpercent) propylene (22 weight percent) ENB (6 weight percent)terpolymerwith specific gravity 0.87, at 22.4° C., Mw/Mn=3.65 and Mw=115, 200,Mooney viscosity 20, commercially available from DuPont Dow ElastomersLCC under the trade designation Nordel 2722 hydrocarbon rubber (aZiegler Natta catalyzed EPDM) containing 2000 ppm Irganox 1076stabilizer with 0.05 weight percent of 4,4′-oxybis(benzenesulfonylazide) CAS# [7456-68-0] for Example 3, but using 0.1 weight percent forExample 4 and no poly(sulfonyl azide) for C.S. B.

EXAMPLES 5 AND 6 AND COMPARATIVE SAMPLE C

The procedure of Example 1 is repeated using an ethylene (71 weightpercent)propylene (23 weight percent) ENB (6 weight percent)terpolymerwith Mw/Mn=2.98 and Mw=173,200, Mooney viscosity 45±6 by ASTM D 1646,commercially available from DuPont Dow Elastomers under the tradedesignation Nordel 2744 hydrocarbon rubber (a Ziegler Natta catalyzedEPDM) containing 2000 ppm Irganox 1076 stabilizer with 0, 0.05, and 0.1weight percent of 4,4′-oxybis(benzenesulfonyl azide) CAS# [7456-68-0]for C.S. C, Example 5, and Example 6, respectively.

TABLE 1 Viscosity measurements in English units Visc 0.1 Visc 100 ViscTan % Visc 0.1 % Visc 10 % Tan poise poise 0.1/100 0.1 Change ChangeChange C.S. A 2.55E+05 1.32E+04 19.30 2.1627 0 0 0 Ex. 1 3.75E+051.36E+04 27.49 1.2659 47 3 −41 Ex. 2 5.18E+05 1.36E+04 37.97 0.838 103 3−61 C.S. B 8.26E+05 1.31E+04 62.84 0.992 0 0 0 Ex. 3 5.92E+05 1.31E+0445.34 1.2753 −28 −1 29 Ex. 4 9.29E+05 1.49E+04 62.55 1.0214 13 13 3 C.S.C 2.07E+06 2.24E+04 92.54 0.6482 0 0 0 Ex. 5 2.18E+06 2.32E+04 94.180.6185 5 4 −5 Ex. 6 3.37E+06 2.33E+04 144.78 0.4572 63 4 −29

TABLE 1b¹ Summary of Melt Rheological Results in metric units (allviscosities in Pa-S (Pascal seconds)) Visc 0.1 Visc 100 Visc Tan % Visc0.1 % Visc 10 % Tan Pa-S Pa-S 0.1/100 0.1 Change Change Change C.S. A2.55E+04 1.32E+03 19.30 2.1627 0 0 0 Ex. 1 3.75E+04 1.36E+03 27.491.2659 47 3 −41 Ex. 2 5.18E+04 1.36E+03 37.97 0.838 103 3 −61 C.S. B8.26E+04 1.31E+03 62.84 0.992 0 0 0 Ex. 3 5.92E+04 1.31E+03 45.34 1.2753−28 −1 29 Ex. 4 9.29E+04 1.49E+03 62.55 1.0214 13 13 3 C.S. C 2.07E+052.24E+03 92.54 0.6482 0 0 0 Ex. 5 2.18E+05 2.32E+03 94.18 0.6185 5 4 −5Ex. 6 3.37E+05 2.33E+03 144.78 0.4572 63 4 −29

For the three EPDM samples prepared using 0.1 weight percentpoly(sulfonyl azide) (Examples 2, 4 and 6), the largest degree ofrheology modification was seen for the Example 2 which was preparedusing metallocene catalyst. The low shear viscosity (viscosity 0.1rad/s) increased by 103 percent over that of the base polymer with thehigher shear viscosities increasing less substantially at 3 percent at100 rad/s and 22 percent at 1000 l/s. Thus, a substantial increase inlow shear viscosity (100 percent at 0.1 rad/s) correlatable withincreases in melt strength was observed for a metallocene based EPDMwith less substantial changes in high shear viscosity (3 percent at 100rad/s) reflecting good processability. The melt rheological behavior,however, shows the largest overall differences between the comparativesamples (not subjected to coupling reactions) due to coupling in thepractice of the invention.

EXAMPLES 7, 8, AND 9, AND C.S. D

The procedure of Example 1 was repeated for Ex. 7, 8, and 9, and C.S. Dexcept that 193 g of Nordel IP NDR 3720 hydrocarbon rubber having acomposition definedin Example 1) and the amounts of4,4′-oxybis(benzenesulfonyl azide) CAS# [7456-68-0] as listed in Table 2were used.

TABLE 2 Effect of Azide Amount on the rheology and Gel content of EPDM %0.1 0.1 Rad 100 Rad Rad 0.1 vis Mooney Vis- Vis- Vis- to 100 SampleAzide Vis- cosity cosity cosity vis N ppm cosity PaS PaS change ratio %Gel C.S. A   0 18.0 2.55E4 1.35E3 18.9 Ex. 7  500 21 3.97E4 1.26E3  5631.5 0.08 Ex. 8 1000 27 5.90E4 1.20E3 131 49.2 0.26 Ex. 9 1500 32.49.20E4 1.37E3 261 67.2 1.5 C.S. D 2000 38.6 1.55E5 1.63E3 506 95.1 34.2

Examples 7-9 and Comparative Samples A-D show that the Mooneyviscosities can be modified significantly for a variety of EPDM's. Therelative amount of poly(sulfonyl azide) used depends on the originalMooney viscosity and diene content. The relative amount of the sulfonylazide is adjusted so that the final product has gel content less than 2percent.

The data in Tables 1 and 2 show that poly(sulfonyl azide) can modify avariety of EPDM's including those made using Ziegler Natta ormetallocene complex catalysts, preferably constrained geometrycatalysts. The results from Table 2 indicate that, in Example 9, theNordel IP 3720 hydrocarbon rubber (made using a constrained geometrycatalyst) modified with 1500 ppm of sulfonyl azide has a higher meltstrength (0.1 Rad shear viscosity) or Mooney viscosity than C.S. B inTable 1, the Nordel 2722 EPDM hydrocarbon rubber, which is known tothose skilled in the art to be used in wire and cable applications. BothExample 9 and C.S. B have a comparable desirable shear thinning effectthat is expressed by the ratio of 0.1 Rad viscosity to 100 Rad shearviscosity. One significance of this result is that the product ofdesired shear thinning effect no longer has to be made in the reactor(by varying reactor conditions and feeds), but can now be madepost-reactor by reaction with a poly(sulfonyl azide). The amount ofpoly(sulfonyl azide) needed for the predetermined final propertiesdepends on the amount of modification needed for the applicationperformance requirements. Higher amounts of poly(sulfonyl azide) canlead to more than optimal gel; therefore, the amount of poly(sulfonylazide) is preferably kept sufficiently low to maintain less than about2.0 weight percent gel. High gel content reduces the processabilityduring fabrication process and reduces the mechanical properties of thefinal parts.

EXAMPLES 10 AND 11 AND COMPARATIVE SAMPLE E

The procedure of Example 1 was repeated using a substantially linearethylene/octene copolymer with I₂=1 g/10 minutes and density of 0.870g/cm³.commercially available from DuPont Dow Elastomers LLC under thetrade designation ENGAGE™ EG8100 with 0, 0.05, and 0.1 weight percent of4,4′-oxybis(benzenesulfonyl azide) CAS# [7456-68-0] for C.S.E, Example10, and Example 11, respectively.

EXAMPLES 12 AND 13 AND COMPARATIVE SAMPLE F

The procedure of Example 1 is repeated using a linear ethylene-propylenecopolymer with Mw/Mn=2.02, Mw=122,000 I₂=1.1 g/10 minutes and density of0.87 g/cm³ commercially available from Mitsui Petrochemical Industriesunder the trade designation Tafmer™ P0480 with 0, 0.05, and 0.1 weightpercent of 4,4′-oxybis(benzenesulfonyl azide) CAS# [7456-68-0] for C.S.F, Example 13, and Example 14, respectively.

TABLE 3 Summary of Melt Rheological Results in metric units (allviscosities in Pa-S (Pascal seconds)) Example or Compara- % Visc % ViscVisc tive Visc 0.1 Visc 100 Visc Tan 0.1 10 % Tan 1000 % Visc SamplePa-S Pa-S 0.1/100 0.1 Change Change Change Pa-S Change C.S. E 9.28E+031.67E+03 5.55 8.2516 0 0 0 416.44 0 Ex. 10 1.89E+04 1.68E+03 11.262.9234 104 1 −65 443.31 6 Ex. 11 4.33E+04 1.87E+03 23.09 1.5487 366 12−81 499.49 20 C.S. F 1.18E+04 2.96E+03 3.98 9.6377 0 0 0 443.31 0 Ex. 125.56E+04 2.54E+03 21.93 1.4587 371 −14 −85 433.64 −2 Ex. 13 7.21E+043.00E+03 24.04 1.2873 511 1 −87 436.59 −2

The results from C.S. E, Example 10, and Example 11 indicate that themelt strength of the elastomer from ethylene-octene copolymer increasessignificantly with the poly(sulfonyl azide) treatment. Similar resultsare obtained for the ethylene propylene elastomer of Examples 12 and 13.

Sample Preparation of C.S. G, C.S. H, Ex.14. Ex.15, and Ex.16

A 200 g mixer commercially available from Haake Inc. under the tradedesignation Rheomix 6000 was used. For Comparative Sample H 193 g sampleof a substantially linear ethylene/octene copolymer with I₂=1 g/10minutes and density of 0.870 g/cm³ commercially available from DuPontDow Elastomers LLC under the trade designation ENGAGE™ EG8100 was meltedin the mixer at 126° C. while being stirred at 20 rpm for 3 minutesuntil all pellets were molten. Then 0.250 weight percent of4,4′-oxybis(benzenesulfonyl azide) CAS# [7456-68-0] was mixed into themolten polymer for 2 minutes at the same stirring speed. After intimatemixing was achieved, the temperature set was adjusted to 160° C. and therotational speed was increased from 20 to 75 rpm over a period of 7minutes and temperature reached a maximum of 190° C. believed to bemainly from friction of stirring. The mixture is held at this highertemperature and high rotational speed for 5 minutes, and then thestirring was decreased to 20 rpm and the mixture was cooled to 150° C.The sample was removed from the Haake and allowed to cool to roomtemperature. This is not an example of the invention because there is26.9 weight percent gel.

The procedure of C.S. H was repeated but using 0.2, 0.15, 0.1 and 0weight percent 4,4′-oxybis(benzenesulfonyl azide)] for Examples 14, 15,and 16, and CS G respectively. Properties of the resulting products weretested and are in Table 4.

TABLE 4 Effect of Azide on Rheolgy and Gel Content for Ethylene OcteneCopolymer sulfonyl Viscosity Example or azide at 0.1 Rad 0.1/100 GELSsample no. (ppm) Pa-s Viscosity MOONEY (percent) C.S. G    0  0.94E4 5.817.6 N/M C.S. H 2500 21.86E4 128.6 84.5 26.9 Ex. 14 2000 11.64E4 62.347.9 0.209 Ex. 15 1500  6.95E4 38.8 32.5 0.165 Ex. 16 1000  3.89E4 23.624.0 0.173 N/M means not measured

The data in Table 4 indicate that poly(sulfonyl azide) is effective inrheology modification of ethylene-octene copolymer elastomers. Theamount of azide can be controlled to make the rheology modifiedethylene-octene copolymer with gel content less than 2 percent. Thecomparison of data of Example 14 and C.S. D indicate that anethylene-octene copolymer has less tendency to form gel than EPDM, thatis, the rheology modified EPDM with 2000 ppm poly(sulfonyl azide)(C.S.D) has much higher gel than ethylene-octene copolymer using the sameamount of poly(sulfonyl azide)(Ex. 14). The data of sample Ex. 14indicate that the rheology modified ethylene-octene copolymer has acomparable shear thinning effect (ratio of viscosity at 0.1 Rad/s to 100rad/s) with Nordel 2722 hydrocarbon rubber (C.S. B), which is known tothose skilled in the art to be used in wire and cable applications.

What is claimed is:
 1. A composition comprising the reaction productformed by heating an admixture containing (1) at least one elastomercomprising ethylene and at least one comonomer which is selected fromalpha olefins having at least 3 carbon atoms, dienes and combinationsthereof and (2) a coupling amount at least one poly(sulfonyl azide) toat least the decomposition temperature of the poly(sulfonyl azide) for aperiod sufficient for decomposition of at least about 80 weight percentof the poly(sulfonyl azide) said reaction product having less than about2 weight percent gel.
 2. The composition of claims 1 wherein coupling isindicated by a viscosity change at a shear frequency of 0.1 rad/sec ofgreater than 5 percent as measured by DMS.
 3. The composition of claim 1wherein at least one elastomer is a ethylene copolymer having at leastone alpha olefin comonomer having at least 3 carbon atoms and at leastone diene comonomer.
 4. The composition of claim 1 wherein at least oneelastomer has a molecular weight distribution less than about
 3. 5. Anarticle which comprises a composition of claim
 1. 6. The article ofclaim 5 wherein the article is formed from a melt.
 7. The process offormation of the article of claim 5 by molding, foaming, or profileextruding.
 8. The article of claim 5 which is a coating for wire orcable, a tube, a gasket, a seal, roofing, a foam or a fiber.
 9. Thearticle of claim 5 which has been calendared.